The purpose is to investigate the auditory perceptual capacities of severely hearing-impaired persons in identification and discrimination of certain acoustic cues of speech. The general method is to compare abnormal and normal audition using tests of auditory discrimination and identification of speech sounds and of corresponding synthetic sound stimuli. The comparisons are to develop new psychoacoustic information on the speech-perception problems of persons with sensorineural hearing loss. Discrimination and identification measures are carried out for pattern differences among vowel sounds, consonant sounds, and sound spectral patterns which vary in time, such as format transitions.